1. Field of the Invention
The present invention generally relates to a multimedia data stream, and more particularly, to a method and an apparatus for synchronizing a multimedia data stream.
2. Description of the Prior Art
When processing a multimedia data stream, it is crucial that the synchronization of data included in the multimedia data stream be accurately controlled. Digital television (DTV) for example, comprises a video data stream, an audio data stream, and a plurality of program clock reference (PCR) values within its multimedia data stream. The PCR values included in the multimedia data stream are utilized by a DTV receiver as a reference basis. The DTV receiver further refers to decoding time stamps (DTS) and presentation time stamps (PTS) included in the video data stream to process the video data stream. Similarly, the DTV receiver also refers to presentation time stamps (PTS) included in the audio data stream to process the audio data stream.
In the prior art, a phase lock loop (PLL) is utilized to generate a local clock. Counter values accumulated through counting the local clock are used as a local clock reference for approaching the program clock reference (PCR) of the multimedia data stream. However, the local clock reference does not accurately approach the PCR of the multimedia data stream, and problems will occur in the synchronization process for the video and audio data streams of the multimedia data stream.